Hollow needles are used for medical applications involving insertion of the needle into a blood vessel or other tissue, especially for the introduction or removal of fluids. Vascular needles are used in medical procedures involving inserting a catheter into a vein or artery. Catheter insertion may be achieved via percutaneous or surgical routes. Catheterization involves single-wall puncture of a vein or artery with a hollow needle, followed by insertion of a guidewire, withdrawal of the needle and insertion of a catheter over the guidewire.
In general, any hollow needle may be used for introducing a catheter into a vein or artery. However, hypodermic needles have long bevels designed for entering a blood vessel to withdraw blood, making them less suitable for inserting a catheter.
Vascular needles generally have thin walls to allow passage of a guidewire without increasing the outer diameter of the needle, and the corresponding size of the puncture hole. Vascular needles generally have a relatively short bevel at the tip with two cutting surfaces.
When a standard vascular needle is inserted into a vein or artery, the bevel cutting surfaces cause a substantially straight-line incision. This type of incision is shown in FIGS. 1-2, labeled “Prior Art”. Using the numbers on a clock face for reference, the incision 10 in a vessel 12 is generally made between the 3 and 9 o'clock positions, as shown in FIG. 1, and must be wide enough to accommodate a cylindrical catheter.
Based on the geometry of inserting a cylindrical object into a straight-line incision, the incision 10 must be longer than the diameter of a cylindrical catheter 14, as shown in FIG. 2. If the incision 10 is too narrow, insertion of the catheter 14 may result in tearing of the vessel wall 12. An incision that is too long may cause excessive bleeding and require suturing after placement of the catheter.
Thus, a need remains for a vascular needle that creates an incision that reduces the risk of tearing when a catheter is inserted.